1. Field of the Invention
The present invention generally relates to an information recording apparatus, an information recording method, an information recording program, a recording medium that can be read and written to by a computer, and circuit parts, suitable for controlling recording power of a recording medium having a constant linear density such as a CD-R (Compact Disk Recordable).
2. Description of the Related Art
There is a CD-R (Compact Disk Recordable) used as a disk-type recording medium with a constant linear velocity. Conventionally, the CD-R is revolved at a constant linear velocity (CLV) to record data thereon. In this case, the relative velocity between the disk-type recording medium and a laser beam is always constant; therefore, once recording conditions such as recording power and recording pulse width are set optimally, these recording conditions do not need to be changed throughout the surface of the disk.
Therefore, normally, test-writing is performed in a specific area at the innermost periphery of the disk, with varying recording power, with which power a recording can be performed at an equal linear velocity throughout the surface of the disk without causing any problem.
However, in the CLV method, as the recording is performed nearer the inner periphery, the revolution rate of the disk needs to be made faster, i.e., the angular velocity of the disk needs to be made higher, making it difficult to revolve the disk at such a high speed. This leads to a higher cost of a drive motor and an increase in noise and vibration; it also becomes difficult to design other servo systems.
Thereupon, several measures have been taken, in which the angular velocity is not made very low at the outer periphery, while the angular velocity is not made so high at the inner periphery. In this case, the linear velocity becomes higher nearer the outer periphery. Hence, a zone constant linear velocity (ZCLV) method, in which a plurality of recording zones are allocated in a face of the disk so that the CLV is applied to the inner periphery and a higher linear velocity is applied to the outer periphery, is applied. Furthermore, there is a constant angular velocity (CAV) method in which the angular velocity of the disk is constant. In the case of CAV, the linear velocity becomes higher nearer the outer periphery.
In any of the above-mentioned measures, the angular velocity at the inner periphery is not made high; therefore, in some cases, a recording is performed at a linear velocity different from the linear velocity at the inner periphery in which test-writing is performed.
In these cases, how to set or arrange the recording power and other recording conditions is a matter of concern.
Accordingly, an apparatus in which a predetermined operation is carried out as a result of the test-writing so that recording conditions of the different linear velocities can be calculated, was developed conventionally. Furthermore, an apparatus to which the following method is applied, was also developed. That is, an objective value in a predetermined recording state and a value corresponding to a regeneration signal from the recording medium are compared so that a recording power is modified based on a result of the comparison during the time that the information is being recorded to the recording medium. The method is called a running OPC since power is modified in real time during the recording in a case where the test-writing is called Optimum Power Control (OPC). It is possible to modify the proper recording power suitably by applying the running OPC in order to prevent the recording sensitivity from being changed based on a change of media sensitivity and a change of wavelength of a light source.
However, there are two methods for recording information. One is a method in which an entire disk is recorded at once. The other is a method in which the information is recorded with a shorter recording unit many times. The latter method is applied relatively frequently. In this case, after the information recording is discontinued, selecting the following recording power to restart recording is a problem.
Conventionally, a value modified the recording power determined by the OPC so as to correspond to a recording linear velocity, which was then used as the restart recording power. However, before the recording is stopped, as a matter of fact, it had already been expected that the recording power would be modified. After the recording is restarted, the running OPC is activated again. It takes some time to modify the proper power. Before the recording power is modified to the proper power, the recording is implemented with an improper power so that recording quality is reduced and thereby an error may occur.
Therefore, it was necessary to set up an initial value of the following recording power so as to have a nearly proper power from the beginning of the time of restarting the recording. In addition, it was necessary to modify the following change of the recording power by the running OPC.
It becomes more difficult to determine the initial value of the recording power in a case where the recording linear velocity is different depending on the radius of the disk, such as CAV or ZCLV. If the initial value of the recording power is calculated based on only the determination value of the OPC, the initial value of the recording power will be different from an amount of modification by the running OPC.